Whenever I use the keyboard in the iOS Simulator, I get about a 5 second delay from when I tap a key and when the input appears. And I get a similar experience with the UIPicker. Everything else runs at normal speed.
This problem only started after I upgraded to the latest version of Snow Leopard. I am currently on 10.6.8. I was using the 4.0 Simulator at the time with XCode 3.2.6.
I have since upgraded to latest XCode 4.2 with the iOS 5.0 Simulator, but problem persists.
My problem is the same as the one reported here:
I am using a MacBook Pro with 2 GHz Intel Core i7 with 4 GB of DDR3.
It looks like an Apple engineer has screwed something up in one of the OS X upgrade. Maybe it has been fixed in Lion, but upgrading to Lion will be a last resort.
Edit:
I have tried completely reinstalling XCode 3.2.6 and 4.2, and I have created several new projects which just have a text field.
Also I am not running any other programs, and my ram usage and cpu cycles are quite low.
It looks like the only solution will be to file a bug with Apple.